Photos, please :-) Lots and lots of water. Make sure you've got a well created that extends beyond the drip line so that the water will soak down at the right location for the feeder roots (which exist at the edge of the canopy and a little beyond - where ever that original canopy existed). Fertilize with a good quality citrus fertilizer, scratch it into the soil very carefully (citrus feeder roots are shallow), top with some compost, and water in well (never fertilize a dry tree). See if that will help to revive your tree.

Patty S.